Tzurot v3 Testing Patterns

Use this skill when: Writing tests, debugging test failures, adding mocks, or working with fake timers.

Quick Reference

# Run all tests
pnpm test

# Run specific service
pnpm --filter @tzurot/ai-worker test

# Run specific file
pnpm test -- MyService.test.ts

# Coverage
pnpm test:coverage

// Basic test structure
import { describe, it, expect, vi, beforeEach } from 'vitest';

describe('MyService', () => {
  beforeEach(() => {
    vi.clearAllMocks();
  });

  it('should do something', () => {
    expect(result).toBe(expected);
  });
});

Core Principles

1. Test behavior, not implementation
2. Colocated tests - MyService.test.ts next to MyService.ts
3. Mock all external dependencies - Discord, Redis, Prisma, AI
4. Use fake timers - No real delays in tests

Essential Patterns

Fake Timers (ALWAYS Use)

beforeEach(() => {
  vi.useFakeTimers();
});
afterEach(() => {
  vi.restoreAllMocks();
});

it('should retry with delay', async () => {
  const promise = withRetry(fn);
  await vi.runAllTimersAsync();
  await promise;
});

Promise Rejections with Fake Timers (CRITICAL)

// ❌ WRONG - Causes PromiseRejectionHandledWarning
const promise = asyncFunction();
await vi.runAllTimersAsync(); // Rejection happens here!
await expect(promise).rejects.toThrow(); // Too late

// ✅ CORRECT - Attach handler BEFORE advancing timers
const promise = asyncFunction();
const assertion = expect(promise).rejects.toThrow('Error'); // Handler attached
await vi.runAllTimersAsync(); // Now advance
await assertion; // Await result

Mock Factory Pattern

// Use async factory for vi.mock hoisting
vi.mock('./MyService.js', async () => {
  const { mockMyService } = await import('../test/mocks/MyService.mock.js');
  return mockMyService;
});

// Import accessors after vi.mock
import { getMyServiceMock } from '../test/mocks/index.js';

it('should call service', () => {
  expect(getMyServiceMock().someMethod).toHaveBeenCalled();
});

Common Mocks

// Discord message
function createMockMessage(overrides = {}) {
  return {
    id: '123',
    content: 'test',
    author: { id: 'user-123', bot: false },
    channel: { id: 'channel-123', send: vi.fn() },
    reply: vi.fn().mockResolvedValue({}),
    ...overrides,
  } as unknown as Message;
}

// Prisma
function createMockPrisma() {
  return {
    personality: { findUnique: vi.fn(), findMany: vi.fn() },
    $disconnect: vi.fn(),
  } as unknown as PrismaClient;
}

// Redis
function createMockRedis() {
  return {
    get: vi.fn().mockResolvedValue(null),
    set: vi.fn().mockResolvedValue('OK'),
    ping: vi.fn().mockResolvedValue('PONG'),
  } as unknown as Redis;
}

Test File Naming

Mock Reset Functions

When to Add Tests

Integration Test Guidance

When Required:

• Database operations with complex queries (joins, transactions)
• Cross-service communication (bot-client → api-gateway → ai-worker)
• Business logic spanning multiple services

When NOT Needed:

• Pure utility functions
• UI/Discord interaction handlers (mock the session/API instead)
• Simple CRUD operations

Future Enhancement: Service-pairing ratchet where every *.service.ts requires *.integration.test.ts

Contract Tests

Contract tests verify API boundaries between services. Located in common-types/types/.

// *.contract.test.ts - Verify schema compatibility
import { PersonaResponseSchema } from './schemas.js';

describe('PersonaResponse contract', () => {
  it('should parse valid API response', () => {
    const response = { id: 'uuid', name: 'Test', preferredName: null };
    expect(() => PersonaResponseSchema.parse(response)).not.toThrow();
  });

  it('should reject invalid response', () => {
    const response = { id: 123 }; // Wrong type
    expect(() => PersonaResponseSchema.parse(response)).toThrow();
  });
});

When to write: New API endpoints, schema changes, cross-service communication.

Purpose: Catch breaking changes before they hit production. If bot-client expects { name: string } but api-gateway returns { displayName: string }, contract tests fail.

Integration Tests

Integration tests verify multiple components working together. Located in tests/integration/.

// Test actual service interactions (with mocked externals)
describe('AI generation flow', () => {
  it('should process job through full pipeline', async () => {
    // Setup: Create test job data
    const jobData = createTestGenerationJob();

    // Act: Process through actual handlers (mocking only AI/Discord)
    const result = await processGenerationJob(jobData);

    // Assert: Verify end-to-end behavior
    expect(result.response).toBeDefined();
    expect(mockDiscordWebhook).toHaveBeenCalled();
  });
});

When to write: Complex workflows, cross-service operations, database interactions.

Key difference:

• Unit tests: Mock all dependencies, test one function
• Integration tests: Use real components (except external APIs like Discord, OpenRouter)

PGLite for Local Integration Tests

Integration tests use PGLite (in-memory PostgreSQL with pgvector) for zero-setup database testing:

# Run integration tests (no DATABASE_URL needed)
pnpm test:integration

# Schema is auto-generated from Prisma
./scripts/testing/regenerate-pglite-schema.sh

Schema Management (CRITICAL):

• Schema SQL is auto-generated from prisma/schema.prisma
• Stored in tests/integration/schema/pglite-schema.sql
• Regenerate after Prisma migrations: ./scripts/testing/regenerate-pglite-schema.sh
• Uses prisma migrate diff --from-empty --to-schema - never write SQL manually

Environment Detection:

Setup in Tests:

import { setupTestEnvironment, type TestEnvironment } from './setup';

let testEnv: TestEnvironment;

beforeAll(async () => {
  testEnv = await setupTestEnvironment();
  // testEnv.prisma, testEnv.redis available
});

afterAll(async () => {
  await testEnv.cleanup();
});

Contract Coverage Audit

The project uses a ratchet system to prevent new APIs from being added without contract tests:

# Check coverage (fails if NEW gaps detected)
npx tsx scripts/testing/audit-contract-coverage.ts

# Update baseline (after adding contract tests)
npx tsx scripts/testing/audit-contract-coverage.ts --update-baseline

# Strict mode (fails on ANY gap)
npx tsx scripts/testing/audit-contract-coverage.ts --strict

How It Works:

1. Finds all Zod schemas in packages/common-types/src/schemas/api/
2. Checks which have .safeParse() calls in contract tests
3. Compares against contract-coverage-baseline.json
4. Fails CI if NEW untested schemas are added

Adding Contract Tests:

// packages/common-types/src/types/MyFeature.contract.test.ts
import { MyResponseSchema } from '../schemas/api/myFeature.js';

describe('MyFeature API Contract', () => {
  it('should validate response structure', () => {
    const response = { id: '123', name: 'Test' };
    expect(MyResponseSchema.safeParse(response).success).toBe(true);
  });

  it('should reject invalid response', () => {
    const invalid = { id: 123 }; // Wrong type
    expect(MyResponseSchema.safeParse(invalid).success).toBe(false);
  });
});

After Adding Tests: Update baseline if needed to remove fixed gaps

Anti-Patterns

// ❌ BAD - Testing private methods
expect(service['privateMethod']()).toBe(value);

// ❌ BAD - Real delays
await new Promise(r => setTimeout(r, 1000));

// ❌ BAD - console.log in tests
console.log('Debug:', value);

// ❌ BAD - Skipping instead of fixing
it.skip('broken test', () => {});

Coverage Requirements (CI Enforced)

# Check coverage locally
pnpm test:coverage

# Specific service
pnpm --filter @tzurot/api-gateway test:coverage

CI Gate: Codecov runs on every PR. Coverage report shows:

• Overall project coverage change
• Per-file coverage for changed files
• Patch coverage (new/modified lines only)

Related Skills

• tzurot-code-quality - Lint rules, refactoring patterns
• tzurot-types - Type-safe test fixtures
• tzurot-git-workflow - Run tests before pushing
• tzurot-observability - Mock logger in tests

References

• Full testing guide: docs/guides/TESTING.md
• Mock factories: services/*/src/test/mocks/
• Global philosophy: ~/.claude/CLAUDE.md#universal-testing-philosophy
• PGLite setup: tests/integration/setup.ts
• Contract audit: scripts/testing/audit-contract-coverage.ts
• Schema regeneration: scripts/testing/regenerate-pglite-schema.sh